110 THE DESICCATION OF LATER GEOLOGICAL TIMES. 



to the writer that it is very probable that the old lake surface had a 

 somewhat greater expansion to the south than is indicated on Mr. King's 

 diagram. 



A very considerable part of the area of Lake Lahontan was occupied by 

 long peninsulas and islands, all of which were narrow, and had the regular 

 north-northeast and south-southwest trend of the ranges of this part of the 

 Great Basin. These islands rose above the surface of the water to an eleva- 

 tion of several thousand feet. It would be difficult to find anywhere upon 

 the surface of the earth, at the present time, a body of water having such 

 marked and interesting orographic features as those of the ancient Lake 

 Lahontan. 



The exact position of the former outlet of this old lake seems not to have 

 been clearly made out. The writer agrees with Mr. King in believing that 

 the probabilities are that it was to the south. Unfortunately the region at 

 the southwestern corner of Nevada is one exceedingly difficult of exploration, 

 owing to its distance from civilization and the almost entire absence of water 

 over an area of many thousand square miles. These difficulties must be 

 taken into consideration, when it is noticed how little is accurately known 

 of the character of the countiy in this direction. 



It must not be supposed, from the great attention paid by the geologists 

 of the Fortieth Parallel and the Wheeler Surveys to the two great ancient 

 lake regions mentioned, that these were isolated or abnormal features of the 

 Great Basin. The whole area lying between these two great bodies of water 

 was formerly occupied by lakes without number. The entire surface of the 

 country is intei'sected by nearly parallel mountain ranges, as an inspection 

 of any good map of the Cordilleras Avill show.* These often rise to the 

 height of several thousand feet above the adjacent valleys, which are usually 

 narrow in proportion to their length, and separated from each other by low 

 divides. These valleys are not always distinctly terraced ; but they have, 

 beyond doubt, been formerly occupied to a greater or less extent by bodies 

 of water. Some of these were isolated and of small dimensions ; others were 

 in connection with similar lakes or lake-like expansions of the rivers, perhaps 

 in some cases fonninsf bodies of water of verv complicated outline. It will 

 be a long time before explorations have been made in this region in suflfi- 



* See map of California and Nevada, by the State Geological Survey of California ; and also the one entitled 

 "Cordilleras" in the Atlas accompanying the Fortieth Parallel Survey Report; this latter was drawn by Mr. 

 Freyhold, and it is by far the best general map of the western side of the United States yet issued. 



